The present invention relates generally to a manner by which to connect an electrical circuit component, such as integrated circuit (IC) package, to a substrate, such as a printed circuit board. More particularly, the present invention relates to a connector, and an associated method, for forming a connection between the circuit component and the substrate. The connector is formed of a metallic material which exhibits physical-memory characteristics. A solderless connection is formed, and, therefore, environmental concerns associated with the use of conventional, lead-base solder materials are obviated.
Advancements in the field of electronic component technologies have permitted the introduction and commercialization of an ever-increasing array of circuits formed of electronic components. Such advancements in electronic component technologies permit, amongst other things, miniaturization of electronic components.
Electronic components include integrated circuits which are typically formed of large numbers of integrated-circuit elements. The integrated-circuit elements are packaged into a single, integrated-circuit package. Integrated-circuit packages, as well as discrete circuit components, are often times mounted to, or otherwise formed in, printed circuit boards, and the resultant assembly forms the electronic circuitry of an electronic device formed therefrom.
The printed circuit board at which the components are mounted, or otherwise formed, typically include conductive traces for electrically interconnecting the components mounted to the circuit board. Conductive, solder material typically forms the conductive traces formed on the printed circuit board. And, the solder material also electrically connects, and affixes, the electronic components mounted to the circuit board.
During assembly of the electronic circuitry, a substrate is first configured to form the printed circuit board. Typically, trace lines are defined upon the surfaces of the substrates, and through holes are formed in the substrate at which connectors of the IC packages and other discrete components are to be positioned during assembly of the electronic circuitry. Once the substrate have been prepared to formed the printed circuit board the IC packages and other discrete components are mounted in position upon the printed circuit board. Thereafter, the components mounted upon the printed circuit board are electrically connected theretogether and affixed in position at the printed circuit board.
Typically, solder connections are formed to connect the components mounted upon the printed circuit board in position thereat as well as sometimes also to form the conductive traces extending along the printed circuit board, thereby to electrically connect different ones of the components theretogether. The solder connections further affix the various components in their respective mounted positions at the printed circuit board.
When the electronic circuitry is mass-assembled in an automated assembly process, the substrates are first prepared, or purchased already-prepared, to form the printed circuit boards. And, the IC packages and other discrete components are mounted upon the printed circuit board using automated machinery. Typically, the solder connections are formed utilizing solder bath techniques in which at least portions of the printed circuit boards, together with the components mounted thereon, are immersed into a pool of heated, and liquefied, solder material. The pool, sometimes referred to as a solder bath, coats portions of the printed circuit board, and the connector leads of the components mounted thereon are coated with electrically-conductive solder material. The printed circuit board is removed out of the solder bath, and the solder solidifies as the solder material cools. Once cooled, the components mounted upon the circuit board are electrically connected theretogether and affixed in position at the printed circuit board.
Conventional solder materials are typically lead (Pb)-based. That is to say, the solder material typically is formed of an alloy including lead. Various environmental and health concerns have been raised regarding lead and the use of lead-based solder materials. While other types of solder materials are available, such alternatives exhibit other disadvantages which limit their usefulness. For instance, silver (Ag)-based solder materials are available. However, the material costs associated with silver-based solder material make its use impractical when cost-minimization is a design goal.
An alternate manner by which to connect an electronic circuit component to a printed circuit board, or other substrate, would therefore be advantages.
It is in light of this background information related to electronic component technologies that the significant improvements of the present invention have evolved.
The present invention, accordingly, advantageously provides apparatus, and an associated method, by which to connect an electrical circuit component, such as an integrated circuit package, to a substrate, such as a printed circuit board.
Through operation of an embodiment of the present invention, a manner is provided for forming a solderless connection for connecting the electrical circuit component to the substrate. Because a solderless connection is formed, environmental concerns associated with the use of lead-based solder material are obviated.
In one aspect of the present invention, a connector is provided for an electrical circuit component, such as an integrated circuit package or a discrete electrical circuit component which is to be mounted at a printed circuit board and form a portion of electronic circuitry. The connector is integrally formed with the integrated circuit package, or other discrete component, and is formed of a pin member in a first configuration to permit insertion thereof into a through hole, or another indent, formed in the substrate. The pin member is formed of a material which exhibits physical-memory characteristics. That is to say, the material of which the pin member is formed is moldable into a first configuration. Application of, e.g., tension and torsion, forces to the connector causes reconfiguring of the pin member into a second configuration. The second configuration is selected, and the external forces are applied to effectuate reshaping of the pin member into the second configuration, such that the pin member engages with a through hole, or other indent, formed into the substrate when the electrical circuit component is mounted thereat.
Subsequent to mounting of the electrical circuit component at the substrate heat energy is applied to the pin member, such as by placing the electronic circuitry, viz., the substrate together with the components mounted thereon, into an oven. When positioned in the oven, and heat energy is generated to elevate the temperature level of the pin member beyond a selected, elevated level, the pin member is reconfigured back into the first configuration. Through appropriate selection of the first configuration into which the pin member is shaped, the pin member can be caused to become affixed to the substrate. Subsequent removal of the electronic circuitry out of the oven, or otherwise permitting cooling of the pin member does not result in a change in configuration of the pin member out of the first configuration. Connection is thereby effectuated to affix in position the electrical circuit component of which the pin members forms a portion in position at the substrate without the use of a solder material.
In another aspect of the present invention, a plurality of pin members are provided. The plurality includes a first and at least a second pin member affixed to an electrical circuit component to form a portion thereof. The first and second pin members are positioned to extend beneath opposing side portions of the circuit component. When the circuit component is mounted at the substrate, each of the pin members is positioned to extend into a through holes or other indents formed in the substrate. When the pin members are heated to be of temperature levels greater than the threshold temperature level, the pin members are reconfigured into their first configurations which cause affixation of the circuit component to the substrate. By positioning the first and second pin members at opposing side portions of the circuit component, the pin members exert clutching forces which clutchingly engage with the substrates. Appropriate positioning of the pin members and selection of the configurations of the pin members in which they are initially shaped causes the clutching forces to be generated in the opposite directions, thereby to facilitate the clutching affixation of the circuit component with the substrate.
In yet another aspect of the present invention, the pin member is first shaped into an elongated camber-leg shaped configuration having a foot pad member positioned at a distal in side thereof. Such a configuration forms the initial configuration of the pin member. The pin member is reshaped into a second configuration which exhibits a lessen amount of camber, the specific shape of which is selected to facilitate insertion of the pin member to extend in to, or through, a through-hole, or other indent, when the electrical circuit component in mounted upon a substrate. When the temperature level of the pin member is elevated beyond the threshold temperature, the pin member is reconfigured into the configuration which exhibits the greater amount of camber. The amount of camber is selected to connect the pin member, and the circuit component affixed therewith to the substrate.
In these and other aspects, therefore, apparatus, and an associated method, is provided for an electronic circuit component positionable upon a substrate and electrically connectable thereto. Connection of the electrical circuit component to the substrate is facilitated. At least a first pin member is affixed to the electrical circuit component to form a portion thereof. The first pin member is affixed to extend downwardly beneath a bottom surface of the electronic circuit component, thereby to engage with the substrate when the electronic circuit component is seated upon the substrate. The first pin member is of a first configuration when at a first temperature and is of a second configuration when heated to at least a second temperature. The first pin member remains in the second configuration subsequent to heating thereof, to at least second temperature. The second configuration into to which the first pin member is configurable facilitates maintenance of connection of the electronic circuit component upon the substrate.
A more complete appreciation of the present invention and the scope thereof can be obtained accompanying drawings which are briefly summarized below, the following detailed description of the presently-preferred embodiment of the invention, and the appended claims.